1. Field of the Invention
The present invention relates to a prefilled syringe, i.e., a syringe previously filled with a medical solution and, more particularly, a prefilled syringe made of glass which is easy to manufacture, simple to assemble, and affords a sterile environment for a medical solution before injection.
2. Description of the Prior Art
When manufacturing a prefilled syringe with a hollow glass tube, a tip for attachment of a needle is formed into a lure tip, i.e., a reduced hollow tube having a tapering outer wall. Such a lure tip has so far been produced as an integral part of a syringe body as shown in FIG. 10 or as a separate member as shown in FIGS. 11 and 12. The separate lure tip member L1 shown in FIG. 11 is molded out of a synthetic resin, fitted in a narrow mouth of a syringe body through a packing P, and then fixed thereto with an aluminum fitting member F. On the other hand, the separate lure member L2 with a skirt portion as shown in FIG. 12 is molded out of a hard plastic material, and press-fitted on a narrow mouth of a syringe body with a rubber stopper R fitted therein.
However, these prefilled syringes have various problems awaiting a solution. For example, the syringe with the lure tip L as shown in FIG. 10 is low in productivity but high in production cost. Since the lure tip L is produced by thermally softening a glass tube and then shaping it into a certain form, the accuracy thereof is not satisfactory. Thus, the tapering outer wall portion of the lure tip mating with a needle hub or female lure connector has to be polished with whetstones to improve the accuracy. This causes lowering of productivity and an increase in production cost since it is difficult to automate the polishing process of the glass syringes and since it is required to perform a functional test for all the produced glass syringes.
The lure tip for the syringe shown in FIG. 11 must be fixed by an aluminum fitting member, which produces fine powder of aluminum during the fixing process. Thus, the syringe has such disadvantages that there is a fear of contamination of an aseptic room or entering pollution by foreign substances, that foreign matter may enter into the medical solution, and that it requires segregated disposal.
On the other hand, it is a general practice to polish the flange portion of the syringe shown in FIG. 12 to the required outside diameter, as the flanged mouth portion requires finishing of high accuracy. Since the lure tip made of hard plastics such as polycarbonate is press-fitted on the mouth portion of the syringe, it occasionally causes cracks in the skirt portion of the lure tip.
When performing injection with the conventional prefilled syringe having a capacity exceeding 20 ml, it is difficult with the hypodermic needle to pierce the skin covering a site to be injected since all of the lure tips of the prior art have to be constructed in a coaxial configuration with respect to the axis of the glass tube.